# Find True Length Size (1 Viewer)

#### machine2035

##### Member
Hey,

I can't seem to find anywhere how to find the true length size from a picture. I remember something to do with making it parallel to the X-X axis (a property which will make it TL in the other view).

Help please, this question can be used as an example.

#### Attachments

• 41.1 KB Views: 630

#### soloooooo

##### Well-Known Member
I can't solve it based on that picture as there are no dimensions given.

It is just 3d trigonometry though.

#### machine2035

##### Member
I can't solve it based on that picture as there are no dimensions given.

It is just 3d trigonometry though.
Can you just make up sizes so I can see how its done? I don't really care as long as I can understand it.

#### gr_111

##### Member
no its quite easy, you just have to project them both to the same plane.

i'm doing a pic, just wait...

you pivot x around until it is horizontal, then project it straight down until it intersects the horizontal line of the top of the beam. Then measure 'y', the blue line, to get the true length.

Last edited:

#### machine2035

##### Member
no its quite easy, you just have to project them both to the same plane.

i'm doing a pic, just wait...

View attachment 26672

you pivot x around until it is horizontal, then project it straight down until it intersects the horizontal line of the top of the beam. Then measure 'y', the blue line, to get the true length.
Awesome, thanks.

I was getting the red line part but just got confused on how far you project it straight down.. I understand now

#### lemon1

##### Member
no its quite easy, you just have to project them both to the same plane.

i'm doing a pic, just wait...

View attachment 26672

you pivot x around until it is horizontal, then project it straight down until it intersects the horizontal line of the top of the beam. Then measure 'y', the blue line, to get the true length.
For some reason i'm not understanding it

#### vinhkn

##### Member
Oh so you use a compass to draw that arc from that point on the beam to when it hits the red line then project straight down. Is the blue line from that point to where it hits the projected line? :S

#### machine2035

##### Member
Just did another one to make sure I was catching on correct.

Can someone confirm this is the correct way to do it. Yellow is the new line which is true length.. Please let me know if its right

#### gr_111

##### Member
You can disregard the vertical line in the bottom view, because since it's vertical, it is already its true length. so just work out the angled section, then add it to the vertical section, like this:

#### machine2035

##### Member
You can disregard the vertical line in the bottom view, because since it's vertical, it is already its true length. so just work out the angled section, then add it to the vertical section, like this:
View attachment 26743
Awesome.. Would my way still get the right answer.. I haven't printed it out so I am not able to measure and thence apply the scale to see what length I get.

#### gr_111

##### Member
I don't think your way would work, because that vertical line is only in one dimension, i.e. only has 'height', and no 'depth' or 'width', but by putting it on the other view you are saying that it does have width or depth.